[Dovecot] weakness in hash salt generation

[Joshua Goodall]

Dovecot has routines for password hashing; two of these, crypt_generate
and md5_generate, both use sizeof(salt_chars) when reducing a random
string to salt.

I became suspicious when I noted that all salts generated are composed
only of "./01".

Unfortunately salt_char is declared static const char * rather than 
static const char [], and so sizeof(salt_chars) is the size of a pointer.

Recommend:


diff -u -r1.8 password-scheme.c
--- password-scheme.c	30 May 2004 03:57:15 -0000	1.8
+++ password-scheme.c	23 Jul 2004 17:05:36 -0000
@@ -15,7 +15,7 @@
 #  include <openssl/sha.h>
 #endif
 
-static const char *salt_chars =
+static const char salt_chars[] =
 	"./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
 
 static buffer_t *schemes_buf;
 

joshua.

-- 
Joshua Goodall                           "as modern as tomorrow afternoon"
joshua at roughtrade.net                                       - FW109
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